. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. GROWTH IN POPULATION OF MYTILUS 47 dimension is greater in the population from southern California at the ft. level (Fig. 1) than in the Alaskan one ( ft. level). The rate of the northern sample is about 45% of the southern one, initially, but the slopes of the two curves are nearly parallel. The mean absolute increase per thirty days for the southern Cali- fornia sample over the period from April 24 to July 30, 1954 was mm.; for the smaller mussels from Alaska (June 26 to September 4, 1952), the increase was
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. GROWTH IN POPULATION OF MYTILUS 47 dimension is greater in the population from southern California at the ft. level (Fig. 1) than in the Alaskan one ( ft. level). The rate of the northern sample is about 45% of the southern one, initially, but the slopes of the two curves are nearly parallel. The mean absolute increase per thirty days for the southern Cali- fornia sample over the period from April 24 to July 30, 1954 was mm.; for the smaller mussels from Alaska (June 26 to September 4, 1952), the increase was mm. In the middle part of the summer, the rate for the southern sample de- 4,0 —, 2 X LU h- cr h- ^ o CfL O I .0 MYTILUS CALI FOR NlANUS SHELL WIDTH SO. CALIF. 1952 FT. SO. CALIF. 1954 FT. SO. CALIF. 1954 FT. ALASKA 1952 F T. I 0 15 30 45 60 75 90 105 120 135 150 165 TIME IN DAYS 180 195 210 FIGURE 2. A comparison of the rate of growth in width of shell in populations of Mytihts californianus from Mount Edgecumbe, Alaska at one intertidal level, and Big Rock, California at two intertidal levels. Each point represents the mean k value for a sample of fifty or more individuals. The initial value is plotted on the day at which the second measurement was made. creases, but is still growing at a rate greater than the one from Alaska, as seen from an extrapolation of the northern curve. Also, the rate of linear increase in shell width is greater in the population from the ft. level from southern California when compared with the population at the ft. level from Alaska (Fig. 2). The rate of the northern sample, again, is about 45% of the southern one. The initial rates of the two samples from southern Cali- fornia are very similar. The 1952 sample shows no decline in rate due to the lack of intermediate points. For the years 1952 and 1954 the mean absolute increase per thirty days was mm. and mm., respectively. The mussels
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
